The Acoustic Brainstem Response (ABR), like other gross responses, represents the summation of the electrical activity produced by cells and fibers in the auditory brainstem as the volley of nerve impulses generated in the auditory nerve fibers progresses rostrally. The waveforms which are summated are determined by the spatial relations between the sources of the potentials and the gross electrode at which the summation occurs, i.e., it is neural elements which summate, not discharges as recorded with microelectrodes at the neural unit. In order to develop a model of the ABR, therefore, one must estimate the form and timing of neural elements at the gross electrode site. A method is proposed to extract the waveform and timing of neural elements from auditory brainstem sites necessary to develop a model of the ABR in the cat. The timing and number of neural elements is expected to vary, depending on the anatomical connectivity of unit classes. Neural elements will be recovered by cross-correlating the voltage recorded by gross electrodes with the discharges of neural units in the inferior colliculus and in the cochlear nucleus complex. The unit discharges will be used to synchronize samples of the voltage on the gross electrode and the resulting waveforms will be compared to the ABR. The cross-correlation waveforms will be categorized on the basis of the timing and number of synchronous events detected. These categories will be compared to the PST histograms and tuning curves of the different units by which the averages were synchronized.